1. Field of the Invention
The present invention relates to an ink jet recording apparatus provided with locking means for fixing a recording head at a capping position.
2. Related Background Art
An ink jet recording apparatus for executing a recording operation by discharging ink from a recording head onto a recording material is known to be provided with a recovery mechanism including capping means, wiping means, suction recovery means or the like, for recovering and maintaining an ink discharge performance of the recording head. Particularly in an ink jet recording apparatus utilizing a recording head mounted on a carriage which reciprocates in a main scanning direction, it is known to utilize, at a predetermined position outside a recording area, a recovery mechanism which includes a slider following the movement of the carriage and moving along a cam surface, and which executes a capping operation by contacting a cap, mounted on the slider, with the recording head. Such recovery mechanism is described for example in U.S. Pat. No. 6,913,340.
There is also known an ink jet recording apparatus including a carriage lock mechanism, which stops (locks) the carriage in a capping position in a continuously stable state, in a state where the recording head is capped with the cap member. Such ink jet recording apparatus is described for example in Japanese Patent Application Laid-open Nos. H09-109379 and H10-278396.
There is also proposed an ink jet recording apparatus in which, in order to stabilize the position of the carriage when it is in the capping position, a lateral face of the carriage is restricted by a locking lever activated by a conveying roller, whereby the carriage is inhibited from leaving the capping state and moving toward the recording area. In such structure, even when an impact is applied externally to the apparatus, the carriage can constantly maintain the capped state, whereby even when the recording apparatus is not used for a prolonged period, a discharge port of the recording head can be protected from ink solidification and can maintain a stable performance.
Also a recovery mechanism described in U.S. Pat. No. 6,913,340 is combined with the above-described carriage locking mechanism and is so constructed that, after a negative pressure is generated by a pump in the cap while the recording head is capped to execute a suction recovery and before the carriage lock is released, the carriage is further advanced deeper in the recovery mechanism then the cap is separated from the recording head to expose the discharge port to the atmosphere, and the conveying roller is driven in the reverse direction. Such structure allows to provide an ink jet recording apparatus capable of realizing a locking function for the carriage and a recovery function by the ink suction, by a simple structure.
Also Japanese Patent Application Laid-open No. H09-109379 discloses such a structure that when the carriage is in a fixed position such as the capping position, a relative position between the cap and the carriage is fixed by a lock pin which engages with the carriage and a cap holder supporting the cap.
However, these prior technologies described above involve following technical issues. The technology disclosed in Japanese Patent Application Laid-open No. H09-109379 is capable of reducing a lateral dimension of the main body of the apparatus, but requires a complex constitution for vertically moving the lock pin, thus increasing the number of components and resulting in an increased cost. Also though the lock pin itself can be driven by the driving power of the conveying roller, the pump and other operating parts require a drive source separate from that for the conveying roller, thereby resulting in an increased cost.
In the technology disclosed in Japanese Patent Application Laid-open No. H10-278396, after the pump is activated in the capped state of the recording head to generate a negative pressure in the cap for executing the suction recovery operation, it is necessary, in retracting the carriage from the recovery mechanism, to rotate the conveying roller in the forward direction for releasing the locking member. As the forward rotation of the conveying roller causes the pump to release the negative pressure, it is not possible to separate the cap from the recording head while maintaining the negative pressure. Therefore, when the cap is separated, the sucked ink may remain in a large amount on a discharge port-bearing face of the recording head. Such residual ink of large amount may result in various problems such as an incomplete ink wiping in a subsequent wiping operation, an ink overflowing into the apparatus, and an ink color mixing in a recording operation after the suction recovery.
In the technology of U.S. Pat. No. 6,913,340, the carriage can be released from the locked state after the suction recovery operation of the recording head, but it is necessary to release the cap while maintaining a negative pressure within the cap, in order to reduce the ink amount remaining on the discharge port-bearing face of the recording head. However a reverse rotation of the conveying roller for executing a suction operation, in order to separate the cap while maintaining the negative pressure within the cap, also operates the locking member, whereby the carriage cannot be moved from the capping position toward the recording area. Thus, there is required an area to allow the carriage to move to a further advanced position from the capping position, whereby the lateral width of the apparatus becomes inevitably larger.
Also in such further advanced position of the carriage from the capping position, the cap naturally becomes open. Therefore, despite of the carriage lock mechanism, a cap opening force is applied in such a direction as to advance the carriage toward the recovery mechanism. Thus, despite of the carriage lock mechanism, the recording head may not be securely capped.